Preparation For Fiberglass Air Filtration Media

ABSTRACT

A system and method of forming fiberglass air filtration media is disclosed which does not require the use of oil additives. A mixture of resin binder, polymer, and dry adhering agent is formed and applied to the fiberglass as it spins onto the drum. Additionally, the fiberglass filtration media density can vary such that the fiber on the air inflow is less dense than the fiber on the air outflow. After oven curing, the finished air filtration media has an improved ability to attract and hold dust and other contaminants.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/151,478, filed on May 10, 2016, now U.S. Pat. No. 9,695,084, whichclaims the benefit of U.S. Patent Application No. 62/179,572, filed onMay 11, 2015.

TECHNICAL FIELD

The present disclosure relates to air filtration media and, moreparticularly, to air filtration media manufactured to a MinimumEfficiency Reporting Value (MERV) 8 rating and above with an initialpressure drop of less than or equal to 0.20 inches water gravity (WG).The MERV 8 rating and greater can be achieved with fiberglass mediawithout the addition of an undesirable oil coating.

BACKGROUND

Today, fiberglass air filtration manufacturing methods and formulationscan involve the use of oil added after the fiberglass media exits thecuring oven to provide for increased entrainment of air contaminantssuch as dust and particulates. Present solutions handle the problem ofcapturing increased amounts of dust using the oil method.

The oil additive is undesirable since the oil makes the process moreexpensive in additive costs, handling costs, and environmental costs andis cosmetically undesirable. Binders are applied to the fibers as theyare wound on the drum. Binder mixtures often are comprised of 65% ureaformaldehyde and 35% water. In other methods, 1 butyl tackifiers may bemixed into a water emulsion and then mixed with a urea formaldehydeemulsion binder. Urea formaldehyde emulsion is typically used as abinder of glass fibers in the fiberglass filtration industry.

Other patents have mentioned the use of a dry tackifier binder such aspolybutene added to a composition to create a tackifier for sprayingfiberglass filtration media. For example, see Miller U.S. Pat. No.6,136,058, entitled “Uniformly Tacky Filter Media,” and Miller U.S. Pat.No. 5,846,603, entitled “Uniformly Tacky Filter Media.” However, theaddition of polybutene, while useful, does not reach the MERV 8 ratingand higher. In fact, the addition of polybutene barely achieves a MERV 7rating by itself and then not routinely. Modigliani U.S. Pat. No.2,546,230, entitled “Glass Product and Method of Making the Same,” andModigliani U.S. Pat. No. 2,729,582, entitled “Method for Making UnwovenFabrics,” both mention the use of additives to the fiberglass media.However, in Modigliani U.S. Pat. No. 2,546,230, the binder cited isbeing utilized for fiber board insulation and is water mixed with ureaformaldehyde resin with the addition of an acrylic resin. In ModiglianiU.S. Pat. No. 2,729,582, the resin is a vinyltrichlorosilane in a 3.5%solution of xylol, which is not suitable for fiberglass filtrationmedia, but rather more suitable for composites. This disclosure presentsa composition that achieves and sustains a MERV 8 rating and higher.

MERV, Minimum Efficiency Reporting Value, commonly known as MERV rating,is a measurement scale designed in 1987 by the American Society ofHeating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to ratethe effectiveness of filters. The scale “represents a quantum leap inthe precision and accuracy of air-cleaner” and allows for improvedhealth, reduced cost and energy efficiency in heating, ventilation andair conditioning (HVAC) design as well as increased efficiency. Forexample, a HEPA filter is often impractical in central HVAC systems dueto the large initial pressure drop the dense filter material causes.Experiments indicate that less obstructive, medium-efficiency filters ofMERV 7 to 13 are almost as effective as true HEPA filters at removingallergens, with much lower associated system and operating costs. Inlike fashion, the addition of a polymer compounded with a dry adherentand a resin binder provides for a filter media without a high initialpressure drop.

The scale is designed to represent the worst-case performance of afilter when dealing with particles in the range of 0.3 to 10micrometers. The MERV rating is from 1 to 16. Higher MERV ratingscorrespond to a greater percentage of particles captured on each pass,with a MERV 16 filter capturing more than 95% of particles over the fullrange.

Shown in FIG. 1 is a table grouping MERV ratings by particle size:

Prior techniques exist however for the addition of resins such asacrylate polymers to polyester pleat filtration media and binder (withno urea formaldehyde). However, acrylate polymers have never beencombined with urea formaldehyde and polybutene and then applied tofiberglass filtration media.

It would be advantageous to provide a system and method of airfiltration formation and media that increase dust holding capacity.

It would also be advantageous to provide a method of formation of MERV 8or higher air filtration media with fiberglass that does not require theuse of oil.

It would further be advantageous to provide a method of controlling thecross-sectional density of the fiber to maximize the dust holdingcapacity of the filter media while controlling the initial pressuredrop.

It would also be advantageous to provide for a finished filter mediathat feels and looks different from fiberglass.

It would also be advantageous to provide for a fiber that is relativelysoft, springy and dry to the touch, with fibers that look more likeplastic than fiberglass.

Thus there remains considerable need for binder compositions thatprovide for less mess and are cosmetically more pleasing to customerswhile providing for increased dust holding capability at a MERV 8 orbetter. Additionally, the fiber should be capable of progressive densitywith a soft springy texture.

SUMMARY

In accordance with the present disclosure, there is provided a systemand method of forming air filtration media that does not involve the useof an oil additive to fiberglass, yet creates a MERV filter rating of 8or better. The manufacturing method of forming the air filtration mediais mentioned in a co-pending U.S. patent application Ser. No.14/181,426, filed on Feb. 14, 2014, which is incorporated by referenceherein.

To achieve MERV 8 or better without undesirable oil additives, apolymer, wherein the polymer is one of a group of polymers consisting ofacrylates and methyl acrylic acids, is added to a dry adhering agentconsisting essentially of a group of polybutene during the fiberglassair filtration media formation. Both the polymer and the dry adheringagent mix in varying percentages with a resin binder (urea formaldehyde)and are applied to the fiberglass as it is spun onto a drum. In varyingthe application rates of the combined binder resin mixed with a polymerselected from a group of polymers formed from acrylic acid ormethyl-acrylic acid and a dry adhering agent, e.g. polybutene in aspecific formulation, so that the end result can be controlled withgreater precision.

Various objects, features, aspects, and advantages of the presentdisclosure will become more apparent from the following description ofthe disclosure, along with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description makes reference to the accompanying figureswherein:

FIG. 1 shows a table grouping MERV ratings by particle size.

FIG. 2 depicts a chemical structure indicative of a selected group ofacrylate polymers, consisting of a 1-butyl, a methyl, an n-butylacrylate and others in a polymeric structure.

FIG. 3 depicts a chemical structure representative of the structures ofacrylic and methyl-acrylic acid which are the basis of themethyl-acrylic polymers discussed herein.

FIG. 4A shows an electron micrograph of a polymer discussed herein.

FIG. 4B shows information presented by an analysis of the polymer byelectron micrograph.

FIG. 5 is a chemical formula for the most common form of an acrylatepolymer 10 utilized in one embodiment of this disclosure.

Other objects, features, and characteristics will become more apparentupon consideration of the following detailed description with referenceto the accompanying figures.

DETAILED DESCRIPTION

The chemical structure shown in FIG. 2 is the general structure that isindicative of a selected group of acrylate polymers, consisting of a1-butyl, a methyl, an n-butyl acrylate and others in a polymericstructure. For purposes of comparison, the IUPAC lists this selection ofacrylates as -prop-2-enoate (either butyl or methyl). The chemicalreaction of a selected polymer with a dry adherent and a resin binder(which also acts as an additional adherent) creates a polymeric-basedtackifying agent with substantial dust holding capabilities. Ingredientsin the acrylates copolymer group all contain the monomers acrylic acidand methyl-acrylic acid or one of their salts or esters. The drawingshown in FIG. 3 is more closely representative of the structures ofacrylic and methyl-acrylic acid which are the basis of themethyl-acrylic polymers discussed.

These ingredients are considered similar in that they are uniformlyproduced in chemical reactions that leave very little residual monomer.Although residual acrylic acid may be as high as 1500 ppm, typicallevels are 10 to 1000 ppm. Concentrations may be as high as 25% if usedas a binder, film former, or fixative; or as low as 0.5% if used as aviscosity-increasing agent, suspending agent, or emulsion stabilizer.

Analysis of polymer 10 (shown in FIG. 5) by electron micrograph presentsthe information shown in FIGS. 4A and 4B.

The structure presented provides a desirable basis for binding andadhesive properties with the carbon and oxygen bonds being of the mostsignificance with the sulfur presenting minimally in the baseformulation. The sodium presents as a salt of the acrylic ormeth-acrylic acid.

The dry adhering agent is a polymer of the group consisting essentiallyof 1-butene and 2-butene and isobutene. The structure of the 1-buteneand the 2-butene is seen in the repeat units, where, in the case of1-butene, the structure is:

-[—CH2-CH(CH2CH3)-]_(n)-

and in the case of 2-butene, the repeat unit structure is:

-[—CH(CH3)-CH(CH3)-]_(n)-

The C4 polymer typically includes various forms of butene, for exampleisobutene, 1-butene, 2-butene, and others, and can contain a smallamount of propene and minor amounts of polymerization byproducts. Forsimplicity, the polymer is referred to herein as polybutene polymer.Typically, isobutene constitutes from about 80% to about 95% of thetotal polybutene polymer. The polybutene polymer has at least one doublebond per molecule.

The thickness of the skinning of the fiberglass on the air outflowsurface and the air inflow surface are controlled such that the skinningprocess on the air outflow can be densified while still maintaining aninitial pressure drop of less than 0.20 WG for the finished fiberglassair filtration media. Furthermore, the skinning on the air inflowsurface can be maintained as thin as varying needs require preventingstray fibers from projecting randomly from the surface. The fiber mediabetween the two skins progressively increases in density such that thefiber on the air inflow is less dense than the fiber on the air outflowof the fiberglass filtration media. Progressive density is achieved byvarying the speed of the traverses of the furnace over the drum. Thisdensity control is achieved in a substantially linear fashion.

After oven curing of the fiber, the finished media feels and looksdifferent from normal fiberglass. It is relatively soft, springy and dryto the touch. The fibers look more like plastic than fiberglass, due inpart to the polymeric spray mixture bound to the fiberglass media. Theprogressive density of the skin of the fiberglass filtration media alongwith the polymer, resin binder and the dry adhering agent mixtureprovide for increased dust holding capability by allowing for properairflow and help to hold the initial pressure drop to 0.20 WG.

The addition of a polymer 10 combined with a dry adhering agent andresin binder increases the ability of the fibers to attract and holddust such that a MERV 8 rating and above can be achieved with asustainably low initial pressure drop of 0.20 WG. This is achieved witha fiberglass based media without the addition of an undesirable oilcoating. The low initial pressure drop is due in part to thesubstantially linear progressive density of the fiberglass media coupledwith the high dust holding capability. This prevents face loading of theskin surface by large particles.

As indicated in the enclosed drawing and discussion, the polymer 10 isan isotactic polymeric acrylate, which is sticky and typically used informulations to aid in viscosity and ability to emulsify. In accordancewith the present disclosure, there is provided a system and method offorming air fiberglass filtration media that does not involve theaddition of oil during the fiberglass manufacture process. A spraycomposition is formed by combining an acrylate polymer 10 (consistingessentially of the group of polymers such as -prop-2-enoate), a dryadhering agent (a polybutene consisting essentially of a group of1-butene, 2-butene, and isobutene), and a resin binder. The spraycomposition is applied during the fiberglass air filtration mediaformation, as the fiberglass is wound onto the rotating drum. Theaddition of a polymer 10 and varying percentages of the dry adheringagent with the resin binder mixture increases the dust holding capacityof the resulting fiberglass filtration media.

The progressive density of the fiberglass media progresses from a lowerdensity of fiberglass media at the air inflow surface to higher densityof the fiberglass media at the air outflow surface. In the preferredembodiment, the fibers are 21-25 microns with a median size of 23microns. However, the principles disclosed herein may be used withfibers of other sizes. The progressive density of the fiberglass media,along with the application of the spray composition, acts to impedelarge particulate movement within the fiberglass media bulk. Thisincreased impedance occurs between the two faces of the skin surfacesfrom the air inflow skin surface to the air outflow skin surface. Theselarge particulates move less freely through the progressively denserfiberglass bulk and are trapped by the lower density in the region ofthe air inflow surface of the fiberglass media. This allows finerparticles to be trapped in the higher density region of the air outflowsurface and outflow side skin.

The spray composition (acrylates, polybutene, and urea formaldehyde) isapplied without clogging and is applied to the fiberglass as it is spunonto a drum. The spray composition may comprise 55-79% ureaformaldehyde, 20-40% polymer compound, and 1-5% polybutene. In thepreferred embodiment, the spray composition comprises 67% ureaformaldehyde resin, 30% polymer compound, and 3% polybutene. The spraycomposition along with the progressive density of the fiberglass mediaprovides an excellent means to capture and hold large dust particulateswhile avoiding the face-loading of the media common in other types offiltration media. By varying application rates of the spray composition,a specific formulation can be achieved that provides for greaterprecision.

The density of the skin surfaces on the air outflow and air inflow canbe controlled while still maintaining an initial pressure drop of lessthan 0.20 WG for the finished filter. The skinning on the air inflowsurface can be maintained as thin as various needs require, preventingstray fibers from projecting randomly from the surface and facilitatingglue adhesion in the customers' filter framing processes. The fiber isthen oven cured. After oven curing, the finished media feels and looksdifferent from fiberglass. It is relatively soft, springy and dry to thetouch. The fibers look more like plastic than fiberglass.

As disclosed herein, a fiberglass filtration media with the ability toattract and hold dust and achieve a MERV 8 rating and above, without theaddition of an undesirable oil coating, is made possible by producing afiberglass filtration media with progressively increasing density fromair inflow to air outflow comprising thin filaments (for example, 21 to25 microns) and adding polymer combined with a dry adhering agent and aresin binder (urea formaldehyde).

Since other modifications and changes varied to fit particular operatingrequirements and environments will be apparent to those skilled in theart, the invention is not considered limited to the examples chosen forpurposes of disclosure, and covers all changes and modifications whichdo not constitute departures from the true spirit and scope of thedisclosure herein.

1-18. (canceled)
 19. A method for producing fiberglass filtration media,comprising: preparing a mixture comprising: an isotactic polymericacrylate; a polybutene; and a urea formaldehyde; and applying themixture to continuous fiberglass filaments.
 20. The method in accordancewith claim 19, comprising: forming the continuous fiberglass filamentsinto a fiberglass media wherein volumetric weight is lower on an airinflow surface of the fiberglass media and volumetric weight is higheron an air exit surface of the fiberglass media.
 21. The method inaccordance with claim 19, comprising: forming the continuous fiberglassfilaments into a fiberglass mat; and expanding the fiberglass mat toform a fiberglass comprising a progressive density of continuousfiberglass filaments between an air inflow surface of the fiberglassmedia and an air exit surface of the fiberglass media.
 22. The method inaccordance with claim 19, wherein the continuous fiberglass filamentscomprise filaments with a diameter of 21 to 25 microns.
 23. The methodin accordance with claim 19, wherein the mixture comprises: from 20 to40 percent isotactic polymeric acrylate; from 1 to 5 percent polybutene;and from 55 to 79 percent urea formaldehyde.
 24. The method inaccordance with claim 19, wherein the mixture comprises: 30 percentisotactic polymeric acrylate; 3 percent polybutene; and 67 percent ureaformaldehyde.
 25. A method for forming air filtration media, comprising:combining an isotactic polymeric acrylate, a dry adhering agent, and aresin binder together to form a composition; spraying the compositiononto continuous fiberglass filaments collected on a surface.
 26. Themethod of claim 25, wherein the dry adhering agent comprises polybutene;and the resin binder comprises urea formaldehyde.
 27. The method inaccordance with claim 25, wherein the mixture comprises: from 20 to 40percent isotactic polymeric acrylate; from 1 to 5 percent dry adheringagent; and from 55 to 79 percent resin binder.
 28. The method inaccordance with claim 25, wherein the mixture comprises: 30 percentisotactic polymeric acrylate; 3 percent dry adhering agent; and 67percent resin binder.
 29. The method in accordance with claim 25,comprising: forming the continuous fiberglass filaments into afiberglass media wherein volumetric weight is lower on an air inflowsurface of the fiberglass media and volumetric weight is higher on anair exit surface of the fiberglass media.
 30. The method in accordancewith claim 25, comprising: forming the continuous fiberglass filamentsinto a fiberglass mat; and expanding the fiberglass mat to form afiberglass comprising a progressive density of continuous fiberglassfilaments between an air inflow surface of the fiberglass media and anair exit surface of the fiberglass media.
 31. The method in accordancewith claim 25, wherein the continuous fiberglass filaments comprisefilaments with a diameter of 21 to 25 microns.